The present invention relates to a fan rotor disk of a turbomachine such as an airplane turbojet engine.
In the known art, a rotor disk is formed at its periphery with an alternation of cavities and of ribs and bears a plurality of blades each formed of an airfoil section connected to a root engaged axially and retained radially in a cavity belonging to the disk. Platforms are fixed between the blades by radial flanges connected to corresponding radial flanges formed on the ribs of the disk.
The dynamics involved in mounting and removing the platforms onto and off the ribs of the disk entails that the platform perform a translational movement along the rib so that orifices in the flanges of the platform engage with pegs or rods provided on the flanges of the disk.
In a turbomachine, the lateral edges of the platforms have to be close enough to the blade airfoil sections to prevent parasitic flow of air toward the disk. The airfoil sections of a fan have a curved profile which means that the lateral edges of the platforms have also to be curved. However, because of the fitting and removal dynamics, there needs to be some clearance between the edges of the platforms and the airfoil sections and this gives rise to air leaks toward the disk. This clearance is particularly large at the axial ends of the platform. Thus, the buildup of blade/platform clearances over the entire disk leads to a reduction in the overall efficiency of the turbomachine.
In the prior art, solutions were focused on restoring the seal between the platform and the blade. However, techniques such as this entail the incorporation of additional components, making the turbomachines heavier.